Jon,
Funny you should mention the one about the granny - that was going around here quite independantly of any movie:-

HOW GRANNY DIED

by Alan Foster (1985)

In the month of January, the weather being fair
Young Jim and Sue went camping, out in the open air.
But as they squeezed their luggage in to the old VW
Sue's Granny said, "I've never camped, do you mind if I come too?"

So they went and bought a roof rack and another sleeping bag
And made some room on the back seat, the springs began to sag.
With their sleeping bags and billy, their esky and their tent
And Granny in the back seat off to the bush they went.

Off to the New England plateau where the nights are cold and damp
They found a spot beside a creek and there they made their camp.
They chatted round the camp fire, the stars were shining bright
Until at last to bed they went, that cold and fateful night.
But it was all too much for Granny, the pace was much too fast,
And sometime in the dead of night old Granny breathed her last.

When Sue awoke next morning and cast her eyes around
She saw Granny laid out in her sleeping bag upon the ground.
Well Sue was broken hearted, her spirits really down,
She said to Jim, "We'll have to take her to the nearest town."

But Granny's limbs had stiffened, (it is a natural law),
And in the car she would not go where she had been before.
To get her in the back seat they saw they had no hope,
So up upon the roof rack they lashed her with some rope.

Because the roads were bumpy with many holes and ditches
They tied her there securely, round turn and two half-hitches.
Well they made it to the township and called upon the Law,
But the cop said, "Pull the other one, I've heard that one before."

So Jimmy tried some reason, "The least that you can do
Is come and have a look out front at our VW."
Well you wouldn't read about it, when they had a look out front
Some mongrel dog had pinched the car; the cop's remark was blunt:
"You nearly had me going, your story had some style,
Now get lost before I throw you in the cooler for a while."

But Sue was rearly frantic, she cried, "The story's true!
And if we don't find Granny I don't know what I'll do."
Her performance was convincing, so they had a look around,
And just around the corner the old Veedub they found.

Whoever swiped the battered bug had stopped to have a perv
At what was on the roof rack and must have lost his nerve.
He'd opened up the sleeping bag, saw Granny lying there
And didn't wait for intros, he just took off like a hare.

Although you won't believe this tale of Granny, Jim and Sue
And of their fateful camping trip, you should because it's true.
I heard it from a bloke whose cousin once removed or two
Knows the man who made the roof rack for the old VW.

Cheers,
Alan